As in the past, our experimental work will be conducted on three levels: (a) enzymological analysis, (b) animal experimentation, and (c) human studies. Topic (a) is serving as a basis for the better understanding of the role of monoamine oxidase (MAO) in the metabolism and function of ocular monoamines. In spite of the "recent upsurge in knowledge of MAO's physico-chemical characteristics, " our insight into the "mechanisms by which MAO acts is still lamentably incomplete." This state of incompleteness of information hindered us at every step on our way to satisfactory understanding of the funding of ocular MAO. To plan to modulate in vivo MAO activity in the anterior segment and retina of the intact rabbit eye and to follow the consequences of these modulations on the rate of aqueous humor formation, on mydriasis, on the dilatation of conjunctival vessels, and on the electroretinogram. More specifically, we try to modify types A and B of ocular MAO separately and to observe the metabolic and functional consequences. Topic (c). We plan to study retinal functions in patients suffering from Parkinson's disease and from (paranoic) schizophrenia. This line of investigation is based on the assumption, that the dopaminergic system of the basal ganglia appears to be involved in the pathogenesis of these diseases.